This invention relates to a developing device using toner as developer, and an image forming apparatus provided with such a developing device.
There is known an image forming apparatus including an image bearing body having a surface on which a latent image is formed, a developing member disposed in contact with the image bearing body which causes the toner to adhere to the latent image, a toner supply member disposed in contact with the developing member, and a toner layer forming member that forms a thin toner layer on the surface of the developing member (see, Japanese Laid-open Patent Publication No. 2004-341122). Further, in order to enhance image quality, it is proposed to control saturated apparent density of the toner by adjusting the kind and amount of cleaning aid added to the toner.
However, in the conventional image forming apparatus, deterioration of image quality may occur in the case where printing is continuously performed. Therefore, a demand for lengthening the lifetime of the image forming apparatus may not be satisfied.